Main thing is that you don't rely on only one. Something that is free may not stay that way. Something irreplaceable needs to be in a few different places and on different media types.
for sure its also backuped in my own hardware.
always have my pictures on 3 different harddrives which are never plugged in at once
Only way to lose all is burn the house down

I thought about an own cloud server but its too energy intensive just for pictures and other private stuff
For personal photos I have:
1. Originals on PC
2. Copies on second photos only drive in the PC
3. Copies on server in garage (and attached NAS device)
4. Copies on external hardrive kept in the car
5. Copies on external hardrives sent to my mum every month or so (depending on holidays/events/etc)
6. Copies on OneDrive (of important images)
I know this sounds very paranoid/excessive but I have seen the effects on people eat the loss of photos of friends, family, pets and events etc. as they cannot be replaced. True that holiday photos could be done again but many can't. Some documents need to be archived but many can be recreated so I only have them duplicated on backup drives and OneCloud.